Simulation-of-GPRS-MS-BS-Interface-Using-Ns-network-SimulatorGPRS-MS-BS接口使用NS网络仿真器的仿真课件

1、Simulation of GPRS MS-BS Interface Using ns-Network SimulatorDual Degree PresentationbyRicha Jain (96D07007)Department of Electrical Engineering,Indian Institute of Technolgy,Mumbai, India.Simulation of GPRS MS-BS InteOutline Introduction to GPRSAbout ns-Network SimulatorScope of the ProjectImplemen

2、tation detailsExperimentsConcluding remarks.Outline Introduction to GPRSThe General Packet Radio ServicePacket switched radio transmission Suited for bursty applications (eg Internet)Data rates upto 170 kbpsRe-uses GSM resourcesLower call set-up times; cheaperThe General Packet Radio ServiGPRS Archi

3、tectureGPRS ArchitectureGPRS Protocol StackGPRS Protocol StackAbout nsPublic domainEvent driven simulatorSplit language OTcl and C+Nodes and links; routing algorithms; queuing schemesProtocols TCP, UDP, IPTraffic generators CBR, Exponential, ParetoBasic mobility support. About nsPublic domainA simpl

4、e ns scriptset ns new Simulator#Creating two nodesset n0 $ns node; set n1 $ns node#Creating a link btwn the nodes; prop delay=10ms; Drop tail.$ns duplex-link $n0 $n1 1Mb 10ms DropTail#Nodes themselves dont send/rx data. Create an agent to do soset cbr0 new Agent/CBR$ns attach-agent $n0 $cbr0#create

5、sinkset null0 new Agent/Null$ns attach-agent $n1 $null0#connect the two agents $ns connect $cbr0 $null0#Tell cbr0 when to start and stop$ns at 0.5 $cbr0 start$ns at 4.5 $cbr0 stop“$ns run A simple ns scriptset ns new Wireless FeaturesMobile node (ad-hoc node)Air interfaceRadio propagation modelAdhoc

6、 routing protocolsMobile IPWireless FeaturesMobile node (Structure of a wireless node in nsStructure of a wireless node iSample script for a wireless simulation# Set up hierarchical routing.# Specify topology.# Create God# Create a Base Station$ns_ node-config -adhocRouting DSR -llType LL -macType 8

7、02.11 -ifqType DropTail -ifqLen 100 -antType OmniAntenna -propType TwoRayGround -phyType WirelessPhy -topoInstance $topo -wiredRouting ON -agentTrace ON -routerTrace ON -macTrace ON -movementTrace OFF -channel $chan_ Sample script for a wireless sSample script for a wireless simulationset BS(0) $ns_

8、 node 1.0.0$BS(0) random-motion 0 $BS(0) set X_ 1.0$BS(0) set Y_ 2.0# create mobilenodes in the same domain as BS(0) $ns_ node-config -wiredRouting OFFset node_(0) $ns_ node 1.0.1$node_(0) base-station AddrParams addr2id $BS(0) node-addr#create and attach Agents TCP/UDP/CBR : :#include movement.$ns_

9、at 10.0 “$node(0) setdest 200.0 150.0 15.0 : : : Sample script for a wireless sScope of the projectWe simulate the network stack for the MS-BS interaction and focus on the handling of radio resources.Scope of the projectWe simulatGPRS Air interfaceTDMAUplink-downlink skew of 3 slotsPhysical channel

10、= a slot on a frequency.Logical channels Broadcast/Control/Data.Multiplexing logical channels onto physical channelsTransmission burstsGPRS Air interfaceTDMAA radio block(RLC PDU)01234567012345670123200bytesTDMAframesTransmission over the air interface (in GPRS)A radio block01234567012345670Features

11、 of our GPRS simulatorThe Set-upA single cellThe wireless node now has LL, RLC, MAC for GPRS.Supports traffic in either direction : MS to BS or BS to MSBS can transmit/receive on multiple frequenciesGPRS simFeatures of our GPRS simulatorAir Interface / ChannelsSeparate uplink/downlink frequencies.TD

12、MA structure with 8 slots per frame.Uplink-downlink skew of 3 slots.User defined options:- number of frequencies- number of GPRS slots per frameSignaling channel slot0, on uplink/downlink frequency 0.GPRS simAir Interface / ChannelsGPRS sTransmission and reception over the air-interfaceRLC PDU size

13、set to 50 bytes = 50 bytes transmitted per slot .Propagation delay set to 0.Timers model transmission and reception.A radio : switched ON during transmission/reception, OFF otherwise.GPRS simTransmission and reception oveSignaling for Call Set-Up and HandlingResource Request Messagefrom MS to BSon t

14、he Random Access channel (slot0, freq0) lock IFQwait only one TDMA frame for replyResource Reply Messagefrom BS to MS on allotted channelupdate vlr_ tableswait till MS receives reply before transmittingGPRS simSignaling for Call Set-Up and Signaling.Resource Release Messagefrom MS to BSon the dedica

15、ted slotclear entrieslater requests will be treated on par with fresh requestsGPRS simSignaling.Resource Release MeResource HandlingSlot Allocation first free slot is alloted.allocation symmetric on uplink and downlink.Slot ReleaseMS initiates message on expiry of slot_release_timer.BS deletes vlr_

16、entries on receipt of message.timer value based on experiments.GPRS simResource HandlingSlot AllocatiDealing with ExceptionsCollisionshappen only on the Random Access channel.BS drops all colliding requests.each MS waits one TDMA frame, then backs off for a random interval.Slot level errorserror mod

17、el introduced.users may include/not; user defined rate.Multiple ARP requestssecondary requests dropped.GPRS simDealing with ExceptionsCollisiExperimentsStudying the average packet delayScenarioObservationsInferencesGPRS simExperimentsStudying the averagAverage packet delay for various data ratesGPRS simAverage packet delay for varioAverage packet delay for various data ratesGPRS simAverage packet delay for varioAverage packet delay vs data generation ratesGPRS simAverage packet delay vs data gSimulations Resource release timerScenarioObservationsInferencesInteraction of LL/RLC and TCPs